1. Field of the Invention
The present invention relates generally to signal measurement systems and, more particularly, to simultaneously invoking automated measurements in a signal measurement system.
2. Related Art
Conventional signal measurement systems such as digital oscilloscopes sample, record and display time-varying analog signals. Samples of an input signal are taken and quantized, and the resultant digital representations are stored in a waveform memory under the control of a sampling clock. The acquired data may be subsequently read out as locations in memory are sequentially addressed by a clock signal to provide digital data which can be converted to a time-varying output signal for a waveform display. The sampling clock may be operated at one of several selectable rates depending upon the frequency content of the input signal. The selection of the portion of the analog input signal which is sampled and stored is determined by appropriate triggering circuitry to enable the operator to display the desired portion of the waveform.
There are many types of display elements which can be presented in signal measurement systems in general and test and measurement instruments in particular. For example, in addition to the waveforms representing the signals currently received at the channel inputs, waveforms referred to as function waveforms may also be displayed. Function waveforms are waveforms created by processing one or more signal waveforms. Such processing may include, for example, performing arithmetic manipulations on a signal waveform or combining multiple input signal waveforms in some predetermined manner. The resulting function waveforms are stored in a display memory for subsequent retrieval and display. In addition, memory waveforms may also be displayed. Memory waveforms are waveforms which have been previously captured and stored in a memory device of the signal measurement system. In addition to the above waveforms, other display elements such as marker indicators, trigger indicators, etc., are typically displayed.
A primary function provided by signal measurement systems in the analysis of signals is to enable an operator to perform an automated measurement of a desired signal parameter. Automated measurements allow an operator to quickly and accurately determine values of key attributes of acquired signals without the use of manual calculations. Automated measurements are also a useful and productive technique for characterizing electrical signals using common, well-understood quantities such as peak-to-peak voltage, rise time and frequency. In addition, automated measurements are often used to verify that a given circuit or hardware component as satisfies established performance specifications.
To invoke an automated measurement of a signal waveform displayed in a conventional signal measurement system, a number of operator actions are typically required to be performed. These include the performance of one or more actions to select a desired measurement, followed by additional actions to identify a waveform on which to perform the measurement, referred to herein as the source waveform. In addition to associating the selected measurement with a selected waveform, additional information often needs to be specified. This information may include, for example, the portion or extent of the source waveform over which the selected measurement is to be applied. This extent most often corresponds to a certain time period of the source waveform.
Conventional techniques for invoking oscilloscope measurements often involve the use of push-button keys on the instrument""s front panel. A measurement is selected by depressing a dedicated key with the associated measurement""s name printed on or above it. A source waveform is subsequently identified, either by pressing a key associated with a particular channel, or by turning a knob that scrolls through a list of possible sources.
In another conventional approach, the desired measurement is selected by pressing a multifunction xe2x80x98softkeyxe2x80x99 having a currently-assigned function of invoking a given measurement. Typically, the softkey is located near a textual or graphical display whereat the key""s current function is displayed. With this approach, the current function of the softkey must first be assigned through the activation of a xe2x80x98menuxe2x80x99 or xe2x80x98setupxe2x80x99 key. The menu/setup key may be a fixed function key located on the front panel, or may itself be a softkey having a currently-assigned function of assigning functions to one or more other softkeys. In such conventional systems, source waveform selection is typically accomplished with still additional softkey operations. In other conventional instruments, a hybrid solution is employed. For example, in one conventional approach, measurement selection is accomplished with fixed functions keys while source waveform selection is performed using softkeys.
As noted, in addition to selecting the measurement and source waveform, oftentimes a specific region of the source waveform must be selected by the user. Typically, this is achieved by the operator selecting a desired horizontal extent of the source waveform for measurement. For example, an individual pulse among a series of pulses may need to be selected to measure the period of the signal. Conventional signal measurement systems employ several different methods to select a specific waveform extent or region. In one conventional approach, measurements are applied to the first cycle of the displayed waveform beginning with the left-most pulse. In these systems, the horizontal position controls must be adjusted by the user so that the pulse of interest appears at the left-most position on the waveform display prior to invoking the measurement on the waveform.
In other conventional approaches, a set of marker indicators (visual lines with adjustable vertical and horizontal positions) must be activated and positioned such that the markers bound the region of the source waveform to be measured. Yet another technique is to eliminate the need for region selection by adjusting both horizontal scale and position and, perhaps, the trigger specification, such that only the pulse of interest appears on the waveform display.
There are a number of drawbacks to these latter conventional approaches. First, these conventional techniques require multiple key presses and/or knob turns to be implemented in a specified sequence in order to properly invoke a measurement. Not only is such an arrangement difficult to understand and operate, considerable time is consumed performing the requisite steps to obtain a desired measurement. This is particularly problematic when a number of measurements are to be performed on different regions of many waveforms. Moreover, the it requirement to select a region or horizontal extent often places additional sequencing constraints on the overall invocation process. Common to many implementations of conventional systems is the requirement that the identification of the waveform region must be performed prior to selection of the measurement. Thus, these conventional approaches require both the source waveform and waveform region to be identified prior to the selection of the automated measurement. This is often counter-intuitive to the typical user who most often wants to choose the measurement first, then apply the measurement to a certain extent of a certain displayed waveform.
A further drawback to the above conventional approaches is the limited indications provided to the user with instructions and feedback. For example, certain measurements are only applicable to certain types of waveforms. Conventional systems typically provide no indications to notify a user whenever an attempted application of a particular measurement to a particular waveform is incorrect. As a result, the user may navigate through a significant series of softkey layers to select the source waveform, manipulate various knobs to identify the region to measure, and then again navigate among a number of softkeys to select the measurement. It is not until after these operations are performed that a determination is made as to whether an allowable waveform/measurement assignment has been requested. As a result, the user must periodically repeat a significant number of operator actions to invoke a proper measurement on a desired waveform.
These drawbacks are particularly burdensome when the operator is to invoke a number of measurements either on the same or different source waveforms. For example, an operator may need to measure the same signal parameters of multiple waveforms or may need to perform a series of measurements of specific characteristics of a selected waveform which together provide a desired characterization of the waveform. To perform such a series of measurements in conventional systems, very complex procedures must be performed to successively select particular waveforms, waveform regions and measurements. As a result, these systems are time consuming to use and difficult for the novice or infrequent user to operate and understand.
In addition, performing multiple measurements of multiple waveforms requires a large number of operator actions to be performed. To perform several automated measurements on multiple waveforms, conventional signal measurement systems generally require an operator to perform the series of actions described above to invoke each automated measurement on each waveform. As a result, to perform several automated measurements on several waveforms, the number of operator actions significantly increases. For example, if 5 operator actions are required to invoke each of 4 desired automated measurements and 3 active waveforms are to be measured, an operator would be required to perform 60 (5xc3x974xc3x973=60) separate actions to invoke each of the desired automated measurement on each of the selected waveforms.
One conventional approach to simultaneously invoking multiple measurements is provided in the Model TDS 500, TDS 600 and TDS 700 series oscilloscopes available from Tektronix, Inc. Although this feature, referred to as the xe2x80x9cSnapshotxe2x80x9d feature, enables an operator to invoke multiple measurements, there are a number of drawbacks to this technique which make it impractical in many applications.
To begin with, the Tektronix Snapshot feature suffers from the above-noted drawbacks associated with the use of softkeys. Multiple operator actions are required to be performed in a specified sequence in order to properly invoke a Snapshot measurement. In addition, the operator must select the desired source waveform through the performance of still additional softkey operations. As noted, not only is such an arrangement difficult to understand and operate, considerable time is consumed performing the requisite steps to obtain desired measurements.
Another drawback to the Tektronix Snapshot feature is that the measurement results are presented to the operator in a display window that covers a substantial portion of the waveform display, obscuring the waveforms which are being studied. To enable the operator to visualize the results of subsequent operations, the system removes the results display window from the display whenever an operator input is detected. Thus, to preserve; the results of the automated measurements before proceeding to other tasks, an operator must either manually record or print the measurement results. Otherwise, the operator must reinvoke the measurements after the additional tasks or operations are completed. A further significant drawback to this approach is that it prevents the user from being able to visually associate the waveform and measurement results.
Additional drawbacks relate to the static nature of the Tektronix Snapshot feature. Invocation of the feature results in the performance of the measurements only once; waveform dynamics are not reflected in the displayed measurement results. Thus, the operator must continually re-invoke the automated measurements in order to obtain updated measurement results. In addition to requiring the operator to refresh the automated measurements for known dynamic changes in the waveform, this system fails to alert the operator to unknown dynamic changes in the displayed waveform, allowing the operator to assume previously obtained measurement results are currently valid.
What is needed, therefore, is a simple, intuitive system for performing automated measurements of waveforms regardless of the skill level of the operator. Such a system should also enable operators to invoke user-selected measurements in an efficient manner, and allow the operator to customize the application of such measurements to desired waveforms.
The present invention is a quick measurement apparatus and method for invoking automated measurements in a signal measurement system. In one aspect of the invention, the quick measurement system is configured to apply one or more predetermined automated measurements to each of a plurality of predetermined waveforms sequentially. The multiple measurements are applied to each of the user-selected waveforms in response to a single respective measurement request. The automated measurements measure a respective predetermined extent of each of the selected waveforms. Preferably, each respective measurement request is generated in response to the performance of an associated single operator action. It is also preferable that the quick measurement system is configured to enable a user to define the sequence in which the automatic measurements are applied to the selected waveforms.
In one embodiment, the signal measurement system further includes a graphical user interface for displaying the waveforms and the measurement results on a signal measurement system display. In this embodiment, each of the measurement requests is generated in response to a corresponding selection of a display element on the graphical user interface. In another embodiment, the signal measurement system also includes a front panel keyboard. In this embodiment, each of the respective operator actions includes a depression of a dedicated button on the signal measurement system front panel. Each depression of the dedicated button invokes one of the measurement requests.
In another embodiment, the display includes a waveform display region for displaying the plurality of waveforms, and a measurement display region for displaying the measurement results. The measurement display region is configured so as to not overlay or otherwise interfere with the display of the waveforms in the waveform display region.
In another aspect of the invention, a quick measurement system for use in a signal measurement system having a display is disclosed. The quick measurement system is configured to simultaneously apply a plurality of user-selected automated measurements to each of a plurality of user-selected waveforms in a predetermined sequence. Each application of the plurality of automated measurements occurs in response to a single measurement request. In one embodiment, the signal measurement system includes a graphical user interface. Here, the measurement request is generated in response to operator -selection of a display item on the graphical user interface, such as a pull-down menu item or an icon. In other embodiments, the signal measurement system includes a control panel. In these embodiments, the measurement request is generated in response to a depression of a dedicated button on the control panel or a selection of a programmable softkey on the measurement system display. Alternatively, the measurement request is automatically generated, for example at power on of the signal measurement system.
In another aspect of the invention, a method for sequentially applying one or more predetermined automated measurements to a plurality of predetermined waveforms in a signal measurement system having a display is disclosed. The method includes the steps of: (a) receiving a measurement request; (b) applying the one or more predetermined automated measurements to one of a plurality of the predetermined waveforms corresponding to the measurement request; (c) displaying results of step (b) in a specified region of the display proximate to displayed waveforms; and (d) repeating steps (a) through (c) until all of the one or more predetermined automatic measurements are applied to each of the predetermined waveforms in a predetermined sequence. In one embodiment, the method also includes a step prior to step (a) of determining the predetermined automated measurements. In another embodiment, the method also includes a step prior to step (a) of determining the predetermined waveforms.
In another aspect of the invention, a signal measurement system is disclosed. The signal measurement system includes a signal acquisition system; a display; and a quick measurement system. The quick measurement system includes a measurement manager configured to sequentially apply a plurality of automated measurements to each of a plurality of waveforms in accordance with predetermined measurement parameters. Each of the measurement applications occurs in response to a measurement request, and results in a display of measurement results. The quick measurement system also includes an automated measurement customizer configured to enable an operator to select the plurality of automated measurements and, preferably, the predetermined measurement parameters,
In one embodiment, the signal measurement system also includes a graphical user interface for displaying the waveforms and measurement results on a display of the signal measurement system. Preferably, each of the measurement requests is generated in response to a corresponding selection of a display element on the graphical user interface. In an alternative embodiment, the signal measurement system also includes a front panel keyboard. In this embodiment, each measurement request is generated in response to a single respective operator action. In this embodiment, the operator action is a depression of a dedicated button on the signal measurement system front panel. Preferably, the quick measurement system customizer is also configured to enable a user to define a sequence in which the automatic measurements are applied to the multiple waveforms; that is, the relative sequence in which the source waveforms are measured.
One advantage of the present invention is that only a limited knowledge of the signal measurement system, measurement parameters and measurement invocation procedures is required. As a result, a novice or inexperienced user simply may invoke automated measurements through the activation of a single front panel button or graphical user interface display element. This also eliminates the need for the operator to navigate through graphical user interface menus, softkey menus, dialog boxes, or other features which is time consuming and may also not be familiar to the novice or infrequent user.
Another advantage is that the present invention enables the operator to invoke multiple measurements with the generation of a single measurement request, significantly minimizing the number of operator actions, and complexity of the system. Furthermore, these automated measurements may be applied to multiple waveforms in a predetermined sequence, each application occurring in response to a single operator action. As a result, the operator may select only specific waveforms of interest and simultaneously apply multiple measurements to each of the waveforms in sequence, advancing through all of the selected waveforms in succession quickly and easily.
A further advantage is that the quick measure system enables the operator to customize the invocation of automated measurements, including the quantity and type of measurements which are to be performed, as well as which specific waveforms are to be measured. As a result, the quick measurement system may be customized to satisfy any measurement need of the operator.
Further features and advantages of the present invention as well as the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the drawings, like reference numerals indicate identical or functionally similar elements. Additionally, the left-most one or two digits of a reference numeral identifies the drawing in which the reference numeral first appears.